1. Technical Field of the Invention
The present invention relates to a method, system, and apparatus for controlling the routing of calls in a telecommunications exchange, and in particular for retrieving an incoming call that has been diverted to voice mail.
2. Description of Related Art
Voice mail is one of the most widely used telecommunications services. In a typical telecommunications network, such as a Public Switched Telephone Network (PSTN), switching functions are performed in an exchange that provides connections between particular subscribers and the rest of the telecommunications network. One of the features that is typically offered to such subscribers is personalized voice mail. Thus, instead of relying upon a home answering machine, a subscriber to the network can subscribe to a voice mail service that is provided at a public exchange of the network.
Furthermore, with the exception of some small organizations, most businesses, government agencies, education institutions, and other sizeable organizations require access to a large number of telephone lines. Instead of obtaining such access using a large number of telephone lines each having a direct connection with a PSTN, such organizations typically use a Private Branch Exchange (PBX). Use of a PBX can provide more efficient access to multiple telephone lines and allows for local, centralized control of telecommunications services. In addition, a PBX generally provides numerous features and services that can be tailored to the needs of each particular organization. A typical PBX, for example, is connected to a voice mail system and provides for the necessary processing and switching to support voice mail services.
Ordinarily, a call placed to a user""s telephone that has a voice mail service will ring a few times. If there is no answer within a specified number of rings, the public exchange or PBX will divert or forward the call to a voice mailbox in the voice mail system that is associated with the user""s telephone. The caller then hears a greeting and is prompted to leave a message. If a message is received, the user""s telephone or voice mailbox is updated to provide an indication that a voice mail message has been left.
Occasionally, the user is temporarily away from his or her telephone or work area but returns in time to hear the last ring or two before the call is diverted to the voice mailbox. Once the call is diverted, however, the user must wait for the caller to leave a message, call the voice mail system to check the message, erase the message, and then return the call if necessary. The extra time and effort required by these circumstances can often be inconvenient and frustrating, particularly if the caller is unavailable by the time the user is able to return the call. Moreover, in some cases, the caller does not leave a message, and thus, the user is unable to determine the identity of the caller.
There is a need, therefore, for a system, method, and apparatus for retrieving a call that has already been diverted by the public exchange or PBX to the user""s voice mail. Such a system, method, and apparatus would allow users to avoid the delay and inconvenience caused by having to wait for a caller to leave a message, listen to the message, and then attempt to return the call. Furthermore, such a system, method, and apparatus would help avoid the situation where the caller is unavailable to answer a returned call and would reduce the likelihood that the user will be unable to determine whose call he narrowly missed.
The present invention comprises a system, method, and apparatus for retrieving a telephone call that has been diverted by a telecommunications exchange from a called user telephone to a voice mail system or to some other destination. Generally, a telecommunications exchange includes a switching matrix for routing calls and a central computer for controlling the switching matrix and for controlling the features and services of the exchange. An incoming call, which is directed toward a particular user station, is received at a telecommunications exchange that serves the user station. In response, the central computer directs the switching matrix to route the call to a line associated with the user station, thereby causing the user station to ring.
If the call is not answered before the occurrence of some triggering event, such as the elapse of a predetermined period of time, the central computer directs the switching matrix to reroute the call to an alternative destination. When this rerouting occurs, the original connection to the user station is dropped. Typically, the alternative destination is a voice mail system, and a voice path is established between the incoming call and a voice mailbox that is associated with the particular user station. Subsequently, a request is received from the user station to retrieve the rerouted call from the alternative destination. In response to this request, the central computer directs the switching matrix to route the call, once again, to the user station. The connection with the alternative destination is dropped, and a voice path is established between the incoming call and the user station.
In a preferred embodiment of the invention, the central computer includes a called line block containing the software unit that handles the user station and a call monitor block containing the software unit that handles the incoming call. When the call is rerouted, the called line block stores a pointer to the call monitor block. Then, when the call retrieve request is received, the called line block contacts the call monitor block using the stored pointer and requests that the call monitor block reconnect the call with the user station. The call monitor block responds by directing the switching matrix to once again route the call to the user station.